In a factory where aluminum is molded using many die-casting machines, an aluminum material is often supplied, not only from within the factory but also from outside of the factory. In such a case, a container storing aluminum in a melt is carried from a factory on the material supply side to a factory on the molding side to supply to each of the die-casting machines the material kept in the melt. For example, published utility model application 1: JP-U-03-31063 (FIG. 1).
The inventors of the present inventions have proposed a technique in which by making use of pressure difference a material is supplied from such container to the die cast machine side. In other words, according to the technology, the inside of the container is pressurized and a molten metal material disposed in the container is discharged outside through a pipe introduced in the container.
Since a container of this kind is necessary to be heat insulating and fire-resistant, the container is provided with a lining inside of a frame made of, for instance, an iron. Inventors of the present invention have developed a technique in which in such a container a flow path for externally supplying a molten metal in the container is buried in a lining and thereby the heat-retention property of the molten metal that flows the flow path is improved. When the heat-retention property of the molten metal in the flow path is improved, there is an effect in that the molten metal is inhibited from solidifying in the flow path therefore clogging of the flow path is prevented.
However, there is a problem in that the lining inside of the container cracks caused by the thermal expansion and the mechanical impact, when the cracking reaches from a space inside the container to the flow path, a gas for applying pressure directly flows through the cracking portion into the flow path, causing an unstable supply. Furthermore, there is also a problem in that the molten metal in a state of containing the gas therein is blown out of the pipe and molten metal with high temperature is splattered in a surrounding area.
A configuration in which a stoke being hanged down to a storing portion of a molten metal from a top surface portion of the container and the stoke being used as a flow path of the molten metal can be considered. However, this kind of a container requires heating (pre-heating) prior to the use thereof and thereby a large thermal load is applied to the stoke during the heating. For this reason, there is a problem in durability, for example, the stoke being cracked easily. Furthermore, when a metal stoke is used to avoid the cracking, the metal is exposed to a high temperature atmosphere created by the heating, as a result, there is another problem in that a hole is easily formed owing to the oxidation.
The present invention was achieved to overcome such problems and intends to provide a container in which a gas for applying pressure does not leak to the flow path that cause a molten metal flow between inside and outside of the container and a method of manufacturing the container.